Underwater wellhead with cement return line



June 15, 1965 J. A. HAEBER ETAL UNDERWATER WELLHEAD WITH CEMENT RETURN LINE Filed June 27, 1962 2 Sheets-Sheet 1 25b 38 26b Ill 2 Ill 250 g 260FIG.|

BY: LI

THEIR AGENT June 15, 1965 J. A. HAEBER ETAL 3,139,100

UNDERWATER WELLHEAD WITH CEMENT RETURN LINE Filed June 27, 1962 2Sheets-Sheet 2 INVENTQRS:

J. A. HAEBER I R. F. PERNER FIG. 2 F. POORMAN, JR. 7

BY: 5. l-'

THEIR AGENT United States Patent M 3,189,1tltl UNDERWATER WELLHEAD WITHCEMENT RETURN LLNE Eohn A. flasher, Houston, Tern, and Raymond F.Perrier,

ltfctairie, and Frank Poorman, .lru, Lafayette, La, assignors to ShellGil ompauy, New York, N.Y., a corporation of Delaware Filed Tune 27,1962, Ser. No. 205,586

7 Qlaims. (Cl. 166-665) This invention relates to apparatus for use indrilling underwater oil and gas wells at offshore locations, andpertains more particularly to apparatus adapted to provide fluidcommunication between a vessel on the surface of a body of water and awellhead assembly positioned on the ocean floor or at a substantialdepth below the surface of the water during early cementing operationsin the well.

In an attempt to locate new oil fields, an increasing amount of welldrilling has been conducted at offshore locations, such for example, asoil the coast of Louisiana, Texas and California. As a general rule, thestring of casing in a well, together with the tubing string or strings,extend to a point above the surface of the water where they are closedin a conventional manner that is used on land wells, with a conventionalwellhead assembly being attached to the top of the casing. Recently,methods and apparatus have been developed for drilling and completingwells wherein both the well casinghead, and subsequently the Wellheadassembly and easing closure device, are located underwater at a depthsufficient to allow ships to pass over them. Preferably, the casingheadand the wellhead closure assemblies are located close to the oceanfloor. In order to install well drilling equipment underwater and carryout well drilling operations on underwater wells at depths greaterthanthe shallow depths at which a diver can easily operate, it isnecessary to design entirely new equipment for this purpose.

Wells drilled in deep water, that is, in water 100 feet or more indepth, are generally drilled from vessels of varying designs commonlyknown as drilling barges or drilling vessels or platforms. One method ofdrilling underwater wells is described in copending patent application,Serial No. 830,538, filed July 30, 1959. In the method described in theabove-identified patent application a shallow hole is first drilled inthe ocean floor and a large-diameter pipe known as a foundation pile ora well conductor pipe is inserted and cemented in the hole. Acasinghead, forming a portion of the wellhead assembly, is generallysecured to the top of the well conductor pipe together with suitableguide means extending from the Wellhead assembly to the vessel on thesurface of the ocean. The casinghead is provided at the head of the wellconductor pipe so that subsequent concentric strings of pipe or casingand tubing may be hung in the well. After continuing drilling operationsto a substantial depth, a string of pipe, often known as surface casing,is inserted into the well conductor pipe and hung from the casinghead ina manner well known to the art. In order to cement the surface casingpipe string in the well, it is necessary to pump cement down through acementing pipe string, extending from the vessel on the surface above,and into the bottom of the surface casing from whence it flows up theannular space between the outside of the surface casing and the boreholewall of the well. In order to displace the cement slurry up the annularspace outside the surface casing string, it is necessary to providefluid discharge means from this annular space up the wellhead. Since theinner casing string or surface casing is seated in the casinghead, it isnecessary to provide discharge ports through the wall of the casingheador through the conductor pipe of Patented June 15, 1965 therein.

In the event of a poor cement job in cementing the surface casing in thewell, formation pressures encountered by the well may attempt to escapeup the annular space between the surface casing and the conductor pipeand escape out the side discharge ports therein or in the easinghead.Thus, it is an object of the present invention to provide valve means ina cement return line from an underwater well casinghead so that the linemay be closed to prevent the escape of well pressures therefrom.

The cement return line which extends from the casinghead and is incommunication with the annular space therein outside the surface casing,generally extends to the vessel at the surface of the ocean. If desired,drilling fluid may be circulated up this line during one stage ofdrilling the well. During well cementing operations, it may be foundthat there has been a breakdown in a porous section of the formationtraversed by the well which may be caused by the great weight of acolumn of cement acting against the formation. If a breakdown of theformation occurred during the drilling of the well, lost circulationadditives would be added to the drilling mud to plug the zone so thatdrilling mud would not be lost to the formation but would return to thevessel. However, due to the greater weight of cement compared todrilling mud, a formation breakdown might occur during cementingoperations.

It is therefore another object of the present invention to provide acement return line assembly on an underwater wellhead whereby fluid orcement returning out the return line can be selectively dumped out ofthe line at substantially the level of the wellhead thereby reducing thechance of a formation breakdown due to the weight of the cement columnand the pressure being applied to it in order to force a returningcolumn of fluid all the way back to the vessel at the surface of theocean.

A further object of the present invention is to provide a cement returnline from an underwater well with a quick disconnect unit whereby themajor fluid control components-of the cement return line assembly can bedisconnected and retrieved and brought back to the drilling vessel afterthe surface casing has been cemented within a well.

It is another object of the present invention to provide a return linefrom an underwater wellhead which can be employed as a choke line duringdrilling operations and as a cement return line during cementingoperations, while at the am .e time being provided with a flow controlvalve selectively operable to open or close the line during emergencyblowouts.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projectionillustrating a floating drilling platform positioned on the surface ofthe ocean with an underwater Wellhead assembly positioned on the oceanfloor; and,

FIGURE 2 is a diagrammatic view taken in longitudinal projection andpartially in cross section illustrating the cement return line assemblyof the present invention.

Referring to FIGURE 1 of the drawing, a drilling platform or vessel 11,of any suitable floatable type is illustrated as floating on a surfaceof a body of water 12 and substantially fixedly positioned over apreselected drilling location by suitable barge positioning means or bybeing anchored to the ocean floor 13 by suitable anchors (not shown)connected to anchor lines 14 and 15. Equipment of this type may be usedwhen carrying on well drilling operations in water depths varying fromabout to 1500 feet or more. The drilling barge is equipped with asuitable derrick 16 as well as other auxiliary equipmerit needed duringthe drilling of a well. The derrick 16 is positioned over a drillingslot or well 13 which extends vertically through the barge in aconventional manner. When using the equipment of the present invention,the slot of the barge 11 may be either centrally located or extendedfrom one edge. However, drilling operations may be carried out over theside of the barge, platform or vessel without the use of a slot.Additionally, it is to be understood that the equipment of the presentinvention may also be used when drilling a well from any suitableoperational base positioned above the surface of the water, such forexample, as from a drilling barge having feet extending to the oceanfloor or from a platform permanently positioned on the ocean floor.

A typical underwater wellhead structure is illustrated in FIGURE 1 ascomprising a base member 21 which is positioned on the ocean floor 13and is fixedly secured to a conductor pipe or larger-diameter wellcasing 22 which extends down into the well, which has been previ ouslydrilled, and is preferably cemented therein. Thus, the base structure 21is rigidly secured to the ocean floor in order to support two or morevertically-extending guide columns 23 and 24 adapted to receive andguide therein guide arms 25 and .26, 25a and 26a, and 25b and 26b, whichare arranged to slide on vertically-extending guide cables 27 and 28.The lower ends of the guide cables 27 and 28 are anchored to the basestructure 21 within the guide columns 23 and 24, while extendingupwardly through the water to the drilling vessel 11 where they arepreferably secured to constant tension hoists 31 and 32. It is to beunderstood that in an emergency a single guide arm or guide cableextending between the base structure 21 and drilling vessel may beemployed to position a piece of equipment on the wellhead, although aguide system having at least three guide cables is preferred.

Centrally positioned above the base plate 21 and fixedly securedthereto, or to the conductor pipe 22, is a well casinghead unit 33 whichis provided with a lateral discharge port to which a cement circulationor fluid return line 34 is connected to provide fluid commmunicationwith the annular space between the inner wall of the easinghead 33 andthe outer wall of another string of pipe, such, for example, as a stringof surface casing 35 which is hung from the interior of the casinghead33. During drilling operations the casinghead is closed by a wellheadconnector unit 35 having one or more blowout preventers 37 connected tothe top thereof with a landing head 38 of a marine conductor pipe 39secured to the top of the blowout preventer. The marine conductor pipe39 extends upwardly through the water to a position above the surfacethereof adjacent the barge 11. During drilling operations a drill pipeextends down through the marine conductor pipe 39, while duringcementing operations the cementing pipe string may be employed whichextends down through the marine conductor pipe. Alternatively, cementmay be pumped down the marine conductor pipe 39 without the use of acementing string.

As shown in FIGURE 2 the cement circulation or fluid return line 34 isprovided with flow control means which may include a check valve 40and/or a remotely-operable flow control valve 41, as well as a dischargeor dump valve 42. The flow control and dump valves 41 and 42 areprovided with suitable remotely-actuatable operators 43 and 44 havingsuitable control lines 45 and 46 which may be in the form of electricaltransmission lines or pressure hoses which may be bundled together at acluster fitting 47 and then extend to the vessel 11 at the surface. Theflow control ring valve 41 and the dump valve 42 may be valves of anysuitable type, one suitable type being six-inch, one thousand p.s.i.type F valves with hydraulic operators manufactured by Cameron IronWorks, Houston, Texas. The valves, for example, valve 42 may be providedwith downwardly extending stem protectors 48 with a vent hole 49 for thevalve.

Suitable conduit disconnect apparatus is provided in the cementcirculation or fluid retrurn line 34 whereby the controllable valves 41and 42 may be recovered together with the preferably flexible upper partof the circulation line 34 after cementing operations have beencompleted. Any suitable conduit disconnect device may be employed suchfor example as telescoping sleeves that are shear pinned together anddetachable by an upward pull on line 34-. However, it is preferred thata remotely-actuatable disconnect unit 51 be employed. The unit showncomprises a tubular body member 52 having a reduceddiameter portion 53which is insertable in a preferably vertically-extending extension 54which is welded to the upper end of the dump valve housing 55. The bodymember 52 of the disconnect unit 51 is provided with a plurality ofoutwardly-extendible latching dogs 56 which are cammed outwardly by thelower end of a downwardlymoving tubular piston 57 slidably mounted forlimited vertical movement in chamber 58 which may be supplied with fluidpressure above and below the piston through conduits 59 and 69. The dogs56 are adapted to engage circumferential grooves 61 in the inner wallprotecting the stem 50 of e of the tubular extension 54.

Fixedly secured to the lower end of the tubular body member 52 of thedisconnect unit 51 is a spider in the form of a plurality ofradially-extending vanes 62 which extend outwardly from a central pin 63which is in surface contact with the top of the closure element or valvemember 64 of the check valve 46. Thus, when the apparatus of the presentinvention is assembled on the vessel to the form shown in FIGURE 2, withthe tubular body member 52 of the disconnect unit 51 latched in thetubular extension 54 of the check valve, the pin 63 holds the closureelement of valve member 64 of the check valve open so that fluid maycirculate past it and through the spaces between the vanes 62 and thenceupwardly through the disconnect unit 51, valve 41 and the upwardextension of a return line 34 which extends to the barge at the surface.The closure element 64 of the check valve is preferably provided withsuitable spring means 65 whereby the closure elements urged upwardly toclose the check valve 40 when the disconnected unit 51 is unlatched fromthe tubing extension 54 and pulled upwardly out of the tubing extension.

During the cementing of a well when fluid is discharged from thecasinghead 33 into the fluid return line 34, the fluid normally flowspast the closure element 64 of the check valve up through the disconnectunit 51 and through the flow control valve 41 and thence to the vesselat the surface. In the event that abnormal pressures are encounteredflow through the line can be shut off by means of the flow control valve41 which is remotely actuatable from the surface. If on the other handit appears that there has been a breakdown of the formation duringcementing of the well so that cement is being lost to the formation andreturn fluid is not being received at the drilling vessel at the surfaceof the ocean, both the flow control valve 41 and the dump valve would beopened so that the return fluid from the well could be discharged intothe ocean at a point adjacent the well, thus eliminating pressure lossesincurred in the return line 34 between the wellhead and the barge aswell as reducing the hydrostatic head of the column of liquid in thereturn line to the barge. After cementing operations have been completedthe conduit disconnect unit 51 is unlatched so that it and the controlvalve assembly above can be withdrawn to the vessel leaving only thecheck valve closing the horizontal run of the fluid return line 34 whileall of the vertical run of the line is recovered at the vessel.

We claim as our invention:

ll. An underwater drilling wellhead assembly fixedly positioned to theocean floor and adapted to have an operational platform positionedsubstantially thereabove, said wellhead assembly comprising (a) atubular well member extending into the ocean floor and fixedlypositioned therein with the upper end thereof extending above the oceanfloor,

(b) side conduit means extending substantially laterally from saidtubular well member and being in communication with the interiorthereof, said side conduit means extending upwardly from said drillingwellhead assembly to said operational platform at the surface of a bodyof water,

(0) conduit disconnect means in said side conduit means at a leveladjacent said wellhead assembly, and

(d) first valve means in said side conduit means between the tubularwell member and the conduit disconnect means,

(e) wherein said side conduit means has fluid discharge port meansthrough the wall thereof downstream of said disconnect means when flowis outwardly from the well and in communication with the ocean on theside of the disconnect means away from the wellhead assemblysubstantially at the level of said wellhead assembly, and there beingremotely actuatable second valve means normally closing said dischargeport means.

2. The apparatus of claim 1 wherein said side conduit means has asubstantially horizontal run for a short distance from the tubular wellmember and then turning to a substantially vertical run which extendsupwardly to the platform at the surface, and wherein at least theconduit disconnect means is positioned in the vertical run.

3. The apparatus of claim 1 wherein said conduit disconnect meanscomprises pipe connector means having disengageable mating portions, oneportion thereof operatively engaging said first valve means to hold itopen when said mating portions of said connector means are engaged.

4. The apparatus of claim 1 wherein said first valve means comprises acheck valve having a closure member engageable with a portion of saidconduit disconnect means and held open thereby when said conduitdisconnect means is engaged.

5. The apparatus of claim 1 including valve operator means mounted onand operatively connected to said second valve means and powertransmission line means extending from said valve operator means to saidoperational platform at the surface.

6. The apparatus of claim 5 including third valve means in said sideconduit means adjacent said discharge port means thereof for controllingfluid flow through said side conduit means.

7. The apparatus of claim 6 including valve operator means on saidsecond and third valve means and operator means on said conduitdisconnect means.

References Cited by the Examiner UNITED STATES PATENTS 2,127,728 8/38Grant 166-76 X 2,923,531 2/60 Bauer et a1. -7 2,970,646 2/61 Knapp etal. 166-665 X 3,064,735 11/62 Bauer et al. 16666.5 3,090,437 5/ 63 Geerl6666.5 3,099,316 7/63 Johnson 166-665 X 3,100,525 8/ 63 Smith et a1.166-2l FOREIGN PATENTS 874,178 8/57 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

1. AN UNDERWATER DRILLING WELLHEAD ASSEMBLY FIXEDLY POSITIONED TO THEOCEAN FLOOR AND ADAPTED TO HAVE AN OPERATIONAL PLATFORM POSITIONEDSUBSTANTIALLY THEREABOVE SAID WELLHEAD ASSEMBLY COMPRISING (A) A TUBULARWELL MEMBER EXTENDING INTO THE OCEAN FLOOR AND FIXEDLY POSITIONEDTHEREIN WITH THE UPPER END THEREOF EXTENDING ABOVE THE OCEAN FLOOR, (B)SIDE CONDUIT MEANS EXTENDING SUBSTANTIALLY LATERALLY FROM SAID TUBULARWELL MEMBER AND BEING IN COMMUNICATION WITH THE INTERIOR THEREOF, SAIDSIDE CONDUIT MEANS EXTENDING UPWARDLY FROM SAID DRILLING WELLHEADASSEMBLY TO SAID OPERATIONAL PLATFORM AT THE SURFACE OF A BODY OF WATER,(C) CONDUIT DISCONNECT MEANS IN SAID SIDE CONDUIT MEANS AT A LEVELADJACENT SAID WELLHEAD ASSEMBLY AND (D) FIRST VALVE MEANS IN SAID SIDECONDUIT MEANS BETWEEN THE TUBULAR WELL MEMBER AND THE CONDUIT DISCONNECTMEANS,